<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <title>阴影渲染</title>
    <style type="text/css">
      html,
      body {
        margin: 0;
        height: 100%;
      }

      canvas {
        display: block;
      }
    </style>
  </head>
  <body onload="draw();"></body>
  <script src="https://cdn.bootcdn.net/ajax/libs/three.js/r128/three.js"></script>
  <script src="./js/controls/TrackballControls.js"></script>
  <script src="./js/libs/stats.min.js"></script>
  <script>
    var renderer;
    function initRender() {
      renderer = new THREE.WebGLRenderer({
        //增加下面两个属性，可以抗锯齿
        antialias: true,
        alpha: true,
      });
      renderer.setSize(window.innerWidth, window.innerHeight);
      //告诉渲染器需要阴影效果
      renderer.shadowMap.enabled = true;
      renderer.shadowMap.type = THREE.PCFSoftShadowMap; // 默认的是，没有设置的这个清晰 THREE.PCFShadowMap
      document.body.appendChild(renderer.domElement);
    }

    var camera;
    function initCamera() {
      camera = new THREE.PerspectiveCamera(
        45,
        window.innerWidth / window.innerHeight,
        0.1,
        1000
      );
      camera.position.set(0, 50, 150);
      camera.lookAt(new THREE.Vector3(0, 0, 0));
    }

    var scene;
    function initScene() {
      scene = new THREE.Scene();
    }

    var light;
    function initLight() {
      scene.add(new THREE.AmbientLight(0x444444));

      light = new THREE.SpotLight(0xffffff);
      light.position.set(60, 30, 0);

      //告诉平行光需要开启阴影投射
      light.castShadow = true;

      scene.add(light);
    }

    function initModel() {
      //上面的球
      var sphereGeometry = new THREE.SphereGeometry(5, 20, 20);
      var sphereMaterial = new THREE.MeshStandardMaterial({ color: 0x7777ff });

      var sphere = new THREE.Mesh(sphereGeometry, sphereMaterial);
      sphere.position.y = 5;

      //告诉球需要投射阴影
      sphere.castShadow = true;

      scene.add(sphere);

      //辅助工具
      var helper = new THREE.AxisHelper(10);
      scene.add(helper);

      //立方体
      var BoxGeometry = new THREE.BoxGeometry(10, 10, 8);
      var cubeMaterial = new THREE.MeshLambertMaterial({ color: 0x00ffff });

      var cube = new THREE.Mesh(BoxGeometry, cubeMaterial);
      cube.position.x = 25;
      cube.position.y = 5;
      cube.position.z = -5;

      //告诉立方体需要投射阴影
      cube.castShadow = true;

      scene.add(cube);

      //底部平面
      var planeGeometry = new THREE.PlaneGeometry(100, 100);
      var planeMaterial = new THREE.MeshStandardMaterial({ color: 0xaaaaaa });

      var plane = new THREE.Mesh(planeGeometry, planeMaterial);
      plane.rotation.x = -0.5 * Math.PI;
      plane.position.y = -0;

      //告诉底部平面需要接收阴影
      plane.receiveShadow = true;

      scene.add(plane);
    }

    //初始化性能插件
    var stats;
    function initStats() {
      stats = new Stats();
      document.body.appendChild(stats.dom);
    }

    //用户交互插件 鼠标左键按住旋转，右键按住平移，滚轮缩放
    var controls;
    function initControls() {
      controls = new THREE.TrackballControls(camera, renderer.domElement);
      //旋转速度
      controls.rotateSpeed = 5;
      //变焦速度
      controls.zoomSpeed = 3;
      //平移速度
      controls.panSpeed = 0.8;
      //是否不变焦
      controls.noZoom = false;
      //是否不平移
      controls.noPan = false;
      //是否开启移动惯性
      controls.staticMoving = false;
      //动态阻尼系数 就是灵敏度
      controls.dynamicDampingFactor = 0.3;
      //未知，占时先保留
      //controls.keys = [ 65, 83, 68 ];
      controls.addEventListener("change", render);
    }

    function render() {
      renderer.render(scene, camera);
    }

    //窗口变动触发的函数
    function onWindowResize() {
      camera.aspect = window.innerWidth / window.innerHeight;
      camera.updateProjectionMatrix();
      controls.handleResize();
      render();
      renderer.setSize(window.innerWidth, window.innerHeight);
    }

    function animate() {
      //更新控制器
      render();

      //更新性能插件
      stats.update();

      controls.update();

      requestAnimationFrame(animate);
    }

    function draw() {
      initRender();
      initScene();
      initCamera();
      initLight();
      initModel();
      initControls();
      initStats();

      animate();
      window.onresize = onWindowResize;
    }
  </script>
</html>
